Locally validated biomarker cutoffs should inform micronutrient deficiency burdens – Authors' reply
Authors: Ty Beal, Gretchen A Stevens, Mduduzi NN Mbuya, Lynnette M Neufeld
Journal: The Lancet Global Health (2023)

Harshpal Singh Sachdev and colleagues raise three concerns about our Article,1Stevens GA Beal T Mbuya MNN et al.Micronutrient deficiencies among preschool-aged children and women of reproductive age worldwide: a pooled analysis of individual-level data from population-representative surveys.Lancet Glob Health. 2022; 10: e1590-e1599Summary Full Text Full Text PDF PubMed Scopus (59) Google Scholar with examples from India. First, they suggest that our analysis of the Comprehensive National Nutrition Survey (CNNS) data (India) overestimated the prevalence of deficiency in at least one sentinel micronutrient. They argue that our projection contrasts with the steady improvement in Indian human development indicators over time. However, the estimates that Sachdev and colleagues refer to are not projections. Rather, we directly computed the prevalence of deficiency in at least one sentinel micronutrient using the CNNS data. Our estimate for non-pregnant adolescent girls aged 15–19 years (89%, 95% CI 86–92) is remarkably similar to the 86% of girls aged 15–19 years with at least one micronutrient deficiency reported by Sethi and colleagues,2Sethi V Lahiri A Bhanot A et al.Adolescents, diets and nutrition: growing well in a changing world.https://www.unicef.org/india/media/2631/file/CNNS-Thematic-Report-Adolescents-Diets-and-Nutrition.pdfDate accessed: January 18, 2023Google Scholar who used the same CNNS data but different adjustments for inflammation and thresholds for deficiency. Sachdev and colleagues’ methods for the suggested overestimate are not given. Their concern about the use of the sociodemographic index to predict unmeasured micronutrients does not apply to our analysis of the CNNS data, which measured biomarkers of all six sentinel micronutrients. This and other methodological details were documented according to the GATHER statement in the Article and appendix.3Stevens GA Alkema L Black RE et al.Guidelines for accurate and transparent health estimates reporting: the GATHER statement.PLoS Med. 2016; 13e1002056Google Scholar Second, Sachdev and colleagues suggest that the statistical biomarker cutoffs used to define micronutrient deficiencies are uncertain and require locally validated functional cutoffs. We agree that statistical biomarker cutoffs are uncertain and might not always reflect functional outcomes, and we have stated these limitations in the Article. Making global and regional prevalence estimates required standard cutoffs across contexts for comparability. We chose published cutoffs that are widely accepted in the field. We welcome additional research on thresholds for identifying micronutrient deficiencies worldwide using a variety of study designs, including those linking micronutrient status to health risks or health status. Importantly, we caution against the suggestion to use a lower threshold for serum ferritin corresponding with iron deficiency anaemia, since there are functional impairments of iron deficiency in the absence of anaemia.4Lynch S Pfeiffer CM Georgieff MK et al.Biomarkers of nutrition for development (BOND)—iron review.J Nutr. 2018; 148: 1001S-1067SSummary Full Text Full Text PDF PubMed Scopus (174) Google Scholar Finally, Sachdev and colleagues warn of knee-jerk policy implementation of universal micronutrient fortification or supplementation rather than dietary diversification in response to so-called shocking deficiencies. In our view, these new estimates warrant collective action to prevent and control widespread micronutrient deficiencies in India and elsewhere. We agree that dietary diversification should be the primary approach to preventing micronutrient deficiencies, and that use of complementary approaches such as fortification and supplementation should be carefully considered where warranted by local context.5Mbuya MN Neufeld LM Developing national strategies to prevent and control micronutrient deficiency: the role of food fortification.in: Venkatesh Mannar MG Hurrell RF Food fortification in a globalized world. Academic Press, Cambridge2018: 29-40Crossref Scopus (6) Google Scholar We declare no competing interests. Locally validated biomarker cutoffs should inform micronutrient deficiency burdensWe read the micronutrient deficiencies burden study by Gretchen Stevens and colleagues (November, 2022)1 with concern, since the stated findings have the potential for unnecessary so-called shockvertising and reactionary policy shifts. For example, the projection made, that 77–92% of preschoolers and non-pregnant women in India have any sentinel micronutrient deficiency, resulting in eroded human potential, contrasts with the steady improvement in Indian human development indicators over time, with attendant improvements in economy, diet, and social welfare programmes. Full-Text PDF Open AccessMicronutrient deficiencies among preschool-aged children and women of reproductive age worldwide: a pooled analysis of individual-level data from population-representative surveysWe estimate that over half of preschool-aged children and two-thirds of non-pregnant women of reproductive age worldwide have micronutrient deficiencies. However, estimates are uncertain due to the scarcity of population-based micronutrient deficiency data. Full-Text PDF Open Access